Catalyst systems for photo-chemical polymerization

ABSTRACT

An improvement in the method of effecting polymerization and particularly visible light photopolymerization of photopolymerizable ethylenic systems, or compositions thereof, by the use of a mixture of a selective combination of photo-oxidant dye material and catalyst cooperative therewith in initiating polymerization in combination with a light sensitizing activator to induce the reaction of said selective combination and to effect more rapid polymerization, and compositions thereof and therefor.

waited States Patent 1 1 3,627,656

[72] lnventors Leroy J. Miller [56] References Cited Cams Park; UNITED STATES PATENTS 3,352,772 1 1/1967 Mao 204/159.24 21 Appl. No. 813,305

3,097,096 7/1963 OsteL... 96/30 [22] Filed Apr. 3, 1969 3,047,422 7/l962 Sites et al.... ll7/93 [45] Patented Dec. 14, 1971 Assi nee "u hes Aircraft Com an 2,989,455 6/1961 Neugebauer et al.. 204/l59.23 g g P y 2,875,047 2/1959 Oster 204/159.23

Culver City, Calif.

Primary Examiner-Murray Tillman Assistant Examiner-Richard B. Turer CATALYST SYSTEMS FOR PHOTO-CHEMICAL Attorneys-James K. Haskell and Alton V. Oberholtzer POLYMERIZATION 9 Claims, No Drawings ABSTRACT: An improvement in the method of effecting [52] U.S. Cl ..204/l59.24,

96/89 96/115 204/5923 252/1883! 252/431 polymerizatlon and partlcularly VlSiblfi light photopolymerlza P 252/431 R 252/437 252/438 252 439 non of photopolymenzable ethylenlc systems, or composltlons I thereof, by the use of a mixture ofa selective combination of [51] int. Cl. Cgggf1/;Jl() photmoxidam dye material and catalyst cooperative therewith in initiating polymerization in combination with a light sen- [50] Field of Search 96/1 15, Smzing activator to induce the reaction of Said Selective bination and to effect more rapid polymerization, and compositions thereof and therefor.

CATALYST SYSTEMS FOR PHOTO-CTEMICAL POLYMERIZATION This invention relates to a discovery and an improvement in a new method of effecting polymerization and compositions therefor. The method provides a more rapid rate of initiating photopolymerization of polymerizable systems comprised of ethylenically unsaturated compounds, by sensitizing the reaction of a photo-oxidant and catalyst combination which causes polymerization, and products therefor and thereof. More particularly, the present invention relates to a method of selectively utilizing a photo-active agent, as a dye material, essentially incapable of initiating polymerization by itself or of acting as a photo-oxidant, but capable of acting as a sensitizer of a polymerization-effecting combination of a photo-oxidant and a catalyst therefor. The polymerization effecting combination, of the dye material and catalyst, receives energy from said selective photo-active agent and thereby becomes able to initiate rapid photopolymerization therewith, or initiate polymerization by said combination upon exposure to light of different wavelengths from that absorbed effectively by the photo-oxidant.

PRIOR ART Photopolymerization of photopolymerizable systems, as photopolymerizable ethylenically unsaturated monomers and polymers with a photosensitive dye and reducing agent therefor is known to the art. Dyes are utilized in these systems to sensitize and effect the polymerization reactions under conditions of illumination by visible light. However, in normally visible light these polymerization reactions usually proceed very slowly and are time consuming. A more rapid method of forming a photopolymer has been described in the prior application of John B. Rust, Ser. Nos. 450,397 and 483,986, now abandoned and replaced by application Nos. 824,902, now Pat. No. 3,573,922, and 824,903, by providing a photo-oxidant dye material and catalyst mixture combination capable of effecting the production of free radical initiators by the absorption of visible light. Consequently, previous mention of dyes and mixtures thereof has been made from the standpoint of their independent photosensitivity in initiating or making more eflicient use of the entire spectrum of visible light for photopolymerization. Thus, each must be desensitized individually to prevent further polymerization after the initiated photopolymerization, in order to retain a photopolymer copy therein.

The monomers, polymers and mixtures thereof, providing polymerizable systems and of a polymerizable character, are mono and polyfunctional compounds generally termed vinyl compounds. Such polymerizable compounds are typified by styrene, butadiene, vinyl chloride, vinylidene chloride, acrylic acid, acrylamide, acrylonitrile, N (hydroxyethyl) acrylamide, methacrylic acid, calcium diacrylate, barium diacrylate, methacrylamide, vinyl acetate, methyl methacrylate, ethyl acrylate, vinyl benzoate, vinyl pyrrolidone, vinyl methyl ether, vinyl butyl ether, vinyl butyrate, N,N'-alkylenebisacrylamides, secondary acrylamides, tertiary acrylamides, mono, di-, or trivalent metal salts of the above acids, and mixtures thereof, including such polymerizable materials and coatings thereof as known to the art.

The dyes utilized in this prior discovery and described as photo-oxidants or photo-oxidant dyes preferably having the general structural formula:

In this formula, R carries a positive charge and is an imonium, alkylimonium, dialkylimonium, or oxonium group, R is hydrogen or an amino, alkylamino, dialkylamino, or hydroxyl group; X is nitrogen or substituted carbon; Y is sulfur, oxygen or substituted nitrogen, and A is any suitable anion. Of the dyes having the above structure, those having the best photooxidant characteristics, and the best for illustrative purposes herein, are the phenothiazine dyes, which have the following structure:

These dyes differ primarily in the R R R and R, groups, which may be hydrogen or alkyl groups (usually one to five carbon atoms). Other substituents may also be present on the aromatic nucleus in addition to those shown. These phenothiazine dyes are generally blue or purple and absorb most strongly visible light in the yellow, orange, and red regions of the spectrum, or in the wavelength region, or frequency range, of from about 5700 A. to about 7000 A. Concentration is preferably on the order of 10 mole to 10 mole of photo-oxidant dye material per liter of the photopolymerizable composition for imaging of photocopy therein. The catalyst portion is preferably in relatively or substantialiy equal molecular proportion thereto, although more or less of each, including catalyst, can be utilized as the particular polymerizable system and results desired are technically considered relative to the different combinations that may be provided for effecting polymerization.

The catalysts, in the photoredox combination are preferably organic sulfinic compounds, triorgano arsines or triorgano phosphines, including the soluble metal salts and alkyl and aryl esters of sulfinic acids and adducts of sulfinic acids with aldehydes. These catalysts in combination with the photo-oxidant dye function as photoredox catalyst systems for effecting photopolymerization of photopolymerizable ethylenic systems and particularly monomers. Therein the dye is an oxidant component, which is inactive in its electronic ground state (in the dark at normal temperatures) but is an oxidant in its photo-excited state. Illustrative of the preferred catalyst are: p-toluenesulfinic acid, benzenesulfinic acid, pbromobenzenesulfinic acid, naphthalenesulfinic acid, 4- acetamidobenzenesulfinic acid, S-salicylsulfinic acid, ethanesulfinic acid, l,4-butanedisulfinic acid, a-toluenesulfinic and the like. The salts of these acids are the soluble sodium potassium, lithium, barium, silver, zinc, and aluminum salts and the like. Appropriate esters are methyl, ethyl, propyl, butyl, benzyl, naphthyl, and the like and the adducts are formed with formaldehyde, acetaldehyde, isobutyraldehyde, heptaldehyde and the like, and suitable mixtures of the above. Triogano-arsines of the character of and triorgano-phosphines of the character of where R, R and R, may be alkyl, aryl, alkaryl, and aralkyl groups may be employed. Such triorgano compounds are exemplified by tributylphosphine or arsine, triphenylphosphine or arsine, dibutylphenylphosphine or arsine, methyldiphenylphosphine or arsine and trioctylphosphine or arsine, including mixtures of the same.

Concentration of the catalyst is preferably on the order of 10 to 10 moles per liter in a photosensitive combination.

dyes of-the ramiiy ofphehothiaizines (which are purple o blue, i l i 1 V i i I ,-thionineiazureik-methlene Treen' 'ithe'adrlgedse me se .d;oiran e;e eilojwgujr O i e p i i'ieneiof. f Dyes which are suitable I for tlils purpose 3 iriel m t sl h s v a i fi r e R,rhodamine=la'acrilinereiand mg tilit whici'lirbauib lightin th'e visi-f f f fm me; f 1 f 1 j r w a i im i s a ip s s l s r t eo h seem; im rovements: and di bases em o i d resent invention 3 improvement 5 i photopoiymerization of jolymerirabie system ueh as methylene: b

I ho'te doxi s tay em; The prope i l imi j h ts-ox dant an a al st-w e i Q i si Sh e s n z ne ye a e Z a a emanation .thereof; in zvrisible light absorbed poorly hy th e photo-oxidant I butstrongly by the sensitizer; initiates photoimaging polyer -;mization=andcauses=it to' proceed:in-iesstimethan'would"'- '"l'l' 'li jotherwise: be required; iTh'ait r is; the use: at effecting a i f i t- 9; m? i photopolymerization by ph'otoimaging as measurablyreduce 9" iit i 9? y "3. i 5.3 i in the poly er forming waitresses scheming the'com ma i z f i i ii? f tion for photo-oxidant dye :maeaa: and semis st. with a sen h u -s e l e e t's c ms i material a we??? by sitizer preferentially reactive therewithwhen the photo-imag- Tit-image I I i 2 z a r a '7 i i @ng fight, is. era wavelength absorbed by thesensitiz r', but not absorbed, or absorbed only weakly by the "photooxida'nt. For example: by; empioying an active photozbxidant dye ma teria =$Uhf3$ phenothiazinedyes which are generally blue'or purple and absorb visible light most stronglyiin the yellowgorange i iandred regions; ior; in the' 5:700iA1t0 7260 A1 region, a rapid gis ffected 'th I" h Sodium p-teluenesulfinate tem era dissolved in distilled wateri(=250 ml.).:

,c'ient, failingto properly use the lightin thelower wayeiength 1 .angess'lhugthe presentiinvention provides an improve men t n; the method ofutiiiizing the lo we I I reen portions; iof ithe =vis'ib1ie spectrum nitia ting polymerization by using a photoredox' eatal yst'systemcom bination. containing a photoactive sensitizer ther'efor as 'em :bodied hereinfor effecting more-rapid photopolymerization; the hotcpokymerizable composition is;irradiate;d with mom ion-in and bout the 4ooo;- 200 rangegor with w hiteligh composed ofa composite mixture of light including that in the wavelength range of about 4000 to about 5700 A. 45

In addition, the present invention also provides for a miX- SOLUTION F ture of light-active photo-oxidant dyes or dye materials, wherein the individually active photopolymerization effecting photo-oxidant is preferably of the family of pheriothiazine sowrrono a (chess g quot was diluted ned n50. gm

:Alzo misaiiq uo't was di solution'Ej" Acridine red (0.0138 g.) was dissolved in ml. of water. A 20 ml. aliquot was diluted to 50 ml. with water to obtain soludyes capable of reacting with the catalyst when activated by 50 non light in the higher wavelength range of about 5700 A. and

higher. Removing or inactivating this photo-oxidant material TABLE 1 desensitizes the entire composition to visible light. However,

. Volume Volume the method herein [8 primarily related to increasing the rate of Test Volume f Volume f Dye f dye f photoinduced polymerization of polymerizable systems and solution solution solution solutions solutions, added, preferably polymerizable monomer systems catalyzed by a designation used photoredox catalyst system comprised of a photo-oxidant G 4- 0 5 C material and a catalyst material. This method comprises incor- H 4. 0 0. 5 {g 8:? None porating as a part of the catalyst system a sensitizer material I 4- 0 0.5 D which normally cannot function as a photo-oxidant in the pho- J 4. 0 5 8:2 252 toredox-catalyst system, and which cannot initiate 0 5 E 0 5 polymerization by itself, but which absorbs light and transfers 4. 0 0. 5 312 i 5 this absorbed energy to the photo-oxidant which is capable of 0 5 F [l 5 5 using this energy to initiate polymerization. This causes polymerization to proceed in a more rapid manner than is possible with the photo-oxidant and catalyst combination, Each of the above test solutions was exposed to light from a In the method and compositions herein described and illussoo'watt tungsten filament p Projected onto the Solutiontratively provided, the added sensitizer which is inactive as a The test Solutions were contained between two glass Plates photo-oxidant accelerates the reaction rate of the polymerizaseparated by a peripheral shim that was 7 mils thick. The tion effectin photo-oxidant and catalyst material because it am nt of light transmitted by the samp e as detected i a absorbs light energy which is otherwise not available to the acphotomultiplier be, n the tr n mit light w re r tive photo-oxidant material and transfers it to the active as a function of time. The test was repeated with fresh portions photo-oxidant and catalyst mixture. As exemplified, it is esof the test solution and with a light filter in the irradiating sential that the additional sensitizing material have a color or beam of light. The filters which were used were identified and sold to the trade as Filtraflex DT RED (9860i Filtraflex DT Green (98607), and Filtrailex DT Blue (986-). The effect of each dye on the rate of polymerization is apparent from the results shown in tables 2,3, and 4:

TABLE 2.-T11E EFFECTS OF ADDING ERIOCHROME CYANINE R Time (sec.) required for Flltraflex Induction transmission to decrease to UT filter period, 'lnst solution designation used see. 50% 25% 10% None 9.6 16.3 22.4 40.6 0 ("WWW blue 8536111131: :2 22:3 33:3 13?? Blue 286. 2 349. 7 392. 1 457. 6 None 6.9 12.1 16.2 27.0 H (methylene blue plus Red 9. 3 19. 0 31.8 83. 2 eriochrome cyanine R). Green... 30. 9 46. 5 58. 4 78. 5 Blue 150. 8 220.1 263. 1 335. 0 I (erloehrome cyanlne R) None. 12% ecrease in transmission after 2,275 see.

' Methylene blue. 1 Methylene blue plus eriochrome cyanine R. 3 Erioehromc cyanlne R.

TABLE 3.THE EFFECT OF ADDING RHODAMINE B Time (sec.) required for Flltraflex Induction transmission to decrease to DT filter period,

Test solution designation used see. 50% 10% gogennnv 7.2 12.8

G (mew-(19m blue) Green 38.3 53. 7 s5. 4 s5, 6 Blue 260 323 361 422 None 6. 9 12.8 18.8 39.6

J (methylene blue plus Red. 9. 8 19.0 34. 8 rhodamine B). Green 32.4 46. 1 57. 6 76.1

, Blue 168 215 251 306 K (rhodamlne B) None 2, 154 2, 523 2, 706 2, 074

TABLE 4.THE EFFECT OF ADDING ACRIDINE RED Time (sec.) required for Filtrafiex induction transmission to decrease to DT filter period, Test solution designation used see. 25% 1 Nogeuhfln 6.3 12.1 19.!) 48.2 7.6 17.4 9.7 G (mflhykm gl eenu 36.8 53. 2 20.1 04. 1 B1ue 251. 2 304.1 339.3 391. 5 N011e. 6. 1 12. 3 21.1 59. 8 L (methylene blue plus Red. 8.4 17.!) 37. 6 101.6 acridine red) G1ee11 31. 7 47. 6 60. 4 87. 7 Blue 219. 4 269. 5 305. 6 360. 4

.\i (acridine red). N0ne An examination of the data in table 2 reveals that the addition of eriochrome cyanine R decreased the period of illumination with white light required by about 26 to 33 percent. With green and blue light, the acceleration of polymerization was somewhat greater, while with red light the effect was more complex, the initial rate being faster than that observed with methylene blue alone. Qualitatively similar, although very much smaller, effects were observed when rhodamine B and acridine red were added to the photosensitive solution.

Tests were made on the following dyes which were found to be inactive in the present invention:

pyronin B, neutral red, alizarin yellow R, titan yellow,

alizarin red S, methyl orange, acid fuchsin, thioflavin T, erythrosin B, basic fuchsin, phenolsulfonphthalein, orange 1V, methyl red, carminic acid, cresol red, nitrophenylazoresorcinol, acridine, orange, safranine O, eosin B, and rose bengal. In each case, mixture with methylene blue caused polymerization to occur either at the same or at a slower rate than methylene blue alone.

Similar tests were also made on acridine yellow, phloxine B, phenosafranine, fluorescein, riboflavin, and proflavin. The admixture of these dyes accelerated the photoinduced polymerization reaction with blue light, and in some cases with white light, but no more than would be anticipated from a summation of the individual rates of polymerization observed when methylene blue and the additional dye were used separately. Thus, these dyes are individually active and can function independently as the dye component of a photoredox catalyst and, in the present invention, in combination with the sensitiang dyes described above.

TABLE 5 Volume Volume Test Volume of Volume of Dye of dye of water solution solution solution solutions solutions, added, designation A, ml. B,ml. used ml ml.-

GI 4.0 0.5 C 0.5 0.5 4.0 0.5 None 4.0 0.5 8:? None J1 4.0 0.5 8:2 None Each of the above solutions was tested as described in example l. A precipitate formed during the preparation of solution H, and the supernatant solution was used in the test. The results are given in table 6.

TABLE 6 Time (500.) required for Flltrafiex Induction transmission to decrease to- DI filter period, Test solution designation used see. 50% 25% 5.8 11.4 19.3 7. 5 16. 2 34. 3 8 1 thy u 32 2 47.0 8 0 205. 6 258. 1 297. 0 348.0 4. 7 9. 0 12. 6 22. 2 11 (methylene blue plus 6. 9 13.3 20.4 43. 4 eriochrome cyrmine R). 24.0 37. 7 46. 8 59. 6 157. 4 231. 0 268. 2 319. 6 7. 3 11. 7 15. 4 23. 3 1| (methylene blue plus 26. 4 41.0 52. 6 74. 2 rhodamine B). 24. 8 33.8 51.8 77. 2 120. 8 160. 8 187. 2 225. 6 5. 9 10. 8 16. 3 35.0 J; (methylene blue plus 9. 2 18. 4 32. 2 70. 8 aeridine red). 23. 8 37. 4 49. 2 64. 6 155. 8 205. 0 230. 6 267. 8

As 1n example I, the acceleration due to the extra dye was EXAMPLE IV greater when blue or green light was used for illumination. At

Solution A the high concentrations used in this example, rhodamine B and acridine red also interfered with the normal course of the photopolymerization. This was apparent from the retarding effect of these dyes when illumination with red light was used.

EXAMPLE ill TABLE 7 Volume Volume Test Volume of Volume of Dye of dye of glycerol solution solution solution solutions solutions, added, designation A, ml. B, ml. used ml. ml

Ga 4.0 0.5 C 0.5 0.5 H: 4.0 0.5 None 13 4.0 0.5 g-g None .1: 4.0 0.5 8'2 None Each of the above solutions was tested as described under example I. The results are given in table 8.

A buffer solution with a pH of 8.0 was prepared by dissolving anhydrous citric acid (0.519 g.) and anhydrous sodium phosphate, dibasic, (27.63 g.) in enough water to make 1000 ml. of solution. Recrystallized acrylamide (90.0 g.) and N,N- methylenebisacrylarnide (13.5 g.) were dissolved in a sufficient quantity of buffer solution to make a monomer solution, solution A with a volume of 200 ml.

Solutions B C D and E These solutions were similar to solutions B, C, E, and F, respectively, in example 1.

Test solutions were prepared from the above solutions as described in table 9.

Nitrogen gas containing a maximum of 10 ppm. of oxygen was passed through each solution for 15 minutes. The solutions were then illuminated under the same conditions with light from a tungsten lamp passed through a Filtraflex DT Blue (986-10) light filter. The periods of illumination required for gelatin to occur provided in table 10.

TAB LE 8 Time (see) required for Filtrafiex Induction transmission to decrease to DT filter period. Test solution designation used see. 5 5% gogmnnn 4.7 9.2 13.5 i e 6. 4 13. n 29. 8 1 (mthylem blue) Greenun 2s. 6 41. 5 52. 4 72. 8 Blue 211 265. 0 298. 7 352. 7 None 4. 0 H. 6 16. 38.4 11.1 (methylene blue plus erio- Red 5 11. .1 22. 2 60. 4 Chrome yanine R). Green 24. 2 a7. 7 49.0 58. 8 Blue. 06.1 135.7 164.8 208.7 4. 3 ll. 4 16. 2 33 I; (methylene blue plus rhoda- 6. 4 13. 5 25. 5 68. 6 mule 17. n 26.6 34. 5 40. 2 J51. 8 140. 2 166 204. 4 4. 2 11.0 20. 4 58. 4 J (methylene blue plus acridine 6.1 15.4 39. 3 117 "-10- 19. 4 31. 0 39. s 56. a 106. 1 154.2 187. 8 230. 8

TABLE 10 Test Solution Designation Period of Illumination (Sec.) Required for gelation E, (Methylene blue) 44 G, (Methylene blue plus 3 l .5

Rhodumine B) H, (Rhodarnine B) L (Methylene blue plus Acridine red) J, (Acridinc red) No gel after 2l00 seconds No gel after M40 seconds Having described the present embodiments of our discovery in accordance with the Patent Statutes, it will now be apparent that some modifications and variations may be made without departing from the spirit and scope thereof. The specific embodiments described are provided by way of illustration and are illustrative of our discovery, invention or improvements which are to be limited only by the terms of the appended sorbing light in a second range of from 5700 to 7200 A. to. form an activated photoredox catalyst combination capa-.

ble of polymerizing said monomers said photo-oxidant dye being selected from compounds of the fonnula:

where R carries a positive charge and is selected from imoni um, alkylimonium, dialkylimonium and oxonium; R is selected from hydrogen, amino, alkylamino, dialkylamino, and hydroxyl; X is selected from nitrogen and substituted carbon, Y is selected from sulfur, oxygen and substituted nitrogen and A is an anion; and

c. an activator for increasing the activity of the combination and rate of polymerization of said vinyl monomer from light in the 4000 to 5700 A. wavelength range comprising a second dye material incapable of forming a photoactive, photoredox catalyst for said monomer in absence of said first dye, but in presence of said first dye and catalyst material redox combination strongly absorbing said light energy in said 4000 to 5700 A. wavelength range and transferring said absorbed light energy to said combination to activate and accelerate the polymerization of said monomer.

2. A system according to claim 1 in which the first photo-oxidant dye is a phenothiazine dye.

3. A system according to claim 1 in which the activator dye is selected from the group consisting of eriochrome cyanine R, rhodamine B, acridine red and mixtures thereof.

4. A system according to claim 3 wherein the first said photo-oxidant dye is selected from the group consisting of methylene blue, thionine, azure B, methylene green, and mixtures of the same.

5. A system according to claim 3 wherein said catalyst material is selected from at least one of the group consisting of an organo sulfinic compound, a triorgano arsine, a triorgano phosphine, the soluble metal salts and alkyl and aryl esters of sulfinic acids and adducts of a sulfinic acid with an aldehyde.

6. A process of photopolymerizing a photopolymerizable vinyl system which is inactive in the dark and contains:

a. a catalyst material selected from the group consisting of organic sulfinic compounds, triorgano-substituted arsines and triorgano-substituted phosphines in combination with;

b. a first photo-oxidant dye weakly absorbing light in a first wavelength range of 4000 to 5700 A. and strongly absorbing light in a second range of from 5700 to 7200 A. to form a photoredox catalyst combination capable of polymerizing said monomers, said photo-oxidant dye being selected from compounds of the formula:

um, alkylimonium, dialkylimonium and oxonium, R' is selected from hydrogen, amino, alkylamino, dialkylamino, and hydroxyl; X is selected from nitrogen and substituted carbon, Y is selected from sulfur, oxygen and substituted nitrogen and A is an anion; and

c. an activator for increasing the activity of the redox combination and rate of polymerization of said vinyl monomer in the 4000 to 5700 A. wavelength range comprising a second dye material incapable of forming a photoactive, photoredox catalyst for said monomer in absence of said first dye, but in presence of said first dye and catalyst material combination strongly absorbing said light energy in said 4000 to 5700 A. wavelength range and transferring said absorbed light energy to said combination to activate and accelerate the polymerization of said monomer; which comprises exposing said system to radiation within the range of 3800 to about 7200 A. containing a wavelength component within the range of 4000 to 5700 A. for a period sufiicient to efi'ect visible, solid polymerization in said system.

7. A process according to claim 1 in which said activator dye is selected from the group consisting of eriochrome cyanine R, rhodamine B, acridine red and mixtures thereof.

8. A process according to claim 7 in which the photo-oxidant dye is a phenothian'ne dye.

9. A process according to claim 7 in which the photo-oxidant dye is selected from the group consisting of methylene blue, thionine, azure B, methylene green and mixtures thereof.

I: P i i ll 

2. A system according to claim 1 in which the first photo-oxidant dye is a phenothiazine dye.
 3. A system according to claim 1 in which the activator dye is selected from the group consisting of eriochrome cyanine R, rhodamine B, acridine red and mixtures thereof.
 4. A system according to claim 3 wherein the first said photo-oxidant dye is selected from the group consisting of methylene blue, thionine, azure B, methylene green, and mixtures of the same.
 5. A system according to claim 3 wherein said catalyst material is selected from at least one of the group consisting of an organo sulfinic compound, a triorgano arsine, a triorgano phosphine, the soluble metal salts and alkyl and aryl esters of sulfinic acids and adducts of a sulfinic acid with an aldehyde.
 6. A Process of photopolymerizing a photopolymerizable vinyl system which is inactive in the dark and contains: a. a catalyst material selected from the group consisting of organic sulfinic compounds, triorgano-substituted arsines and triorgano-substituted phosphines in combination with; b. a first photo-oxidant dye weakly absorbing light in a first wavelength range of 4000 to 5700 A. and strongly absorbing light in a second range of from 5700 to 7200 A. to form a photoredox catalyst combination capable of polymerizing said monomers, said photo-oxidant dye being selected from compounds of the formula:
 7. A process according to claim 1 in which said activator dye is selected from the group consisting of eriochrome cyanine R, rhodamine B, acridine red and mixtures thereof.
 8. A process according to claim 7 in which the photo-oxidant dye is a phenothiazine dye.
 9. A process according to claim 7 in which the photo-oxidant dye is selected from the group consisting of methylene blue, thionine, azure B, methylene green and mixtures thereof. 